(a) Field of the Invention PA1 (b) Description of the Related Art
The present invention relates to a method for manufacturing a liquid crystal display (LCD) panel.
An LCD is one of the most popular flat panel displays (FPDs). The LCD has two panels having two kinds of electrodes and wires for generating electric fields and a liquid crystal layer interposed therebetween. The intensity of the electric field applied to the liquid crystal layer controls the transmittance of incident light.
The wires and electrodes are formed by depositing and patterning conductive thin films. Insulating layers or passivation layers of silicon oxide (SiO.sub.2) or silicon nitride (SiNx) are formed between the wires or between the wires and electrodes to insulate them. An organic insulating layer consisting of materials such as benzocyclobutene (BCB), perfloucyclobutene (PFCB), and acrylic resin has recently been used as a passivation layer to increase the aperture ratio of the LCD and flatness of the layer. As these organic insulating layers have photosensitivity, neither an etching process nor another photoresist layer is needed to pattern these organic insulating layers. Therefore, the overall manufacturing process can be simplified.
However, an organic insulating layer is softer than the conventional insulating layer such as a SiNx layer. Therefore, when forming a contact hole, residues of the organic insulating layer tend to remain. The residues disturb the contact between the two conducting layers through the contact hole and cause a high contact resistance.
Additionally, an organic insulating layer does not as strongly adhere to a transparent conducting layer formed by indium tin oxide (ITO) sputtering. Therefore, the ITO layer may be easily undercut or over-etched when forming a pixel electrode. As a result, the critical dimensions of the eletrodes become irregular.